Fertilizer



Patented Dec. 9, 1924.

. UNITED STATES 1,518,565 PATENT OFFICE.

ALFRED HUTCHINSON COWLES, OF SEWAREN, NEW JERSEY, ASSIGNO'R TO THE ELEC- TRIC SMELTING AND ALUMINUM 00., OF CLEVELAND, O'HIO, A CORPORATION OF OHIO.

FERTILIZER.

No Drawing.

1 '0 all whom it may concern:

Be it known that I, ALFRED HUTCHINSON COWLES, a citizen of the United States, and resident of Sewaren, in the county of Middlesex and State of New Jersey, have invented certain new and useful Improve ments in Fertilizers, of which the following is a specification.

At the present time, soils from the decomposition of plants and manures are known to contain hydrated silica, also artificial mixtures of fertilizers, in many instances,

contain it in indefinite amounts as an acciw dental impurity. Liebig, as early as 1840,

. from his investigations of the composition of the ashes of various plants, thought silica necessary as a-plant food. This resulted in experiments with potassium and sodium silicates to supply silica to augment the growth of grasses, cereals and plants containing very large percentages of silica in their skeletons.

Knop and other plant physiologists, succeeded in growing plants with silica supposed to be absent as a nutriment, and afterwards, when the Law of the minimum? was proven and accepted, silica in any form was eliminated by agricultural chemists as an essential element to use in artificial mineral fertilizers. (Soil conditions and plant growth by E. J. Russel, 1915 edition, pp. 30. 46, 112.)

It is now universally assumed that silica, clay, zeolites and feldspars in soils, furnish a super-abundance of silica and therefore its addition as a fertilizer is unnecessary. These substances and natural silicates are so minutely soluble that the assumption is unwarranted. By annual repeated growths of Vegetation upon uncultivated land, hydrated double silicates, while slowly degrading to clay, furnish to soil waters solu- Application filed September 18, 1917. Serial No. 192,028.

using variable proportions of hydratedsilica contaming more than fifteen (15) per cent of water of hydration obtained from di-calcium silicate to supply deficiencies of soluble silica required for plant growth. Such silicas containing various amounts of water are securable by the action of carbonic and other acids and moisture upon various simple and complex silicates, artificial or natural.

It further consists in the intentional addition orformation of designed proportions of such silica in the preparation of fertilizer mixtures or substances, either by addition of such hydrated silica or such silicates and an acid, with the intentional design of increasing or supplying intended amounts of hydrated silica to such mixtures. My invention or discovery further embodies adding to soils, simple or complex, calcium silicates artificially prepared, characterized in that carbonic acid of the soil waters will decompose said compounds or mixtures with a liberation of hydrated silica of a more soluble type than those hydrated silicas that ordinarily occur in nature as minerals. The

presence of other essential fertilizers such as potash, iron oxide, phosphoric acid and soda as impurities in said complex silicates, is not to be avoided when there is a sufiieient allowance of calcium oxide to silica in the mixture, so that upon the action of carbonic acid and moisture, there shall be formed a large amount of hydrated silica by their decomposition when used.

In my invention, any silicate may be used in any manner so as .to supply to the soil or fertilizer mixtures, designed amounts of available added soluble silica. There are certain silicates and l'nixtures of silicates that can be artificially prepared that will furnish a cheap source of soluble silica. To make my invention clear as to the use of hydrated silica from these specific materials, I explain how to form them and the reasons for their use.

Many suggestions have been made involving the fusion of lime with native potash minerals such as occur in granites or potash schists and green sa'nd lnarls, with a view to render available the potash therein for fertilizer purposes. In such attempts, it was thought necessary to use potash minerals at high potash content and only suflicient lime to displace the molecular weight proportions of potassa that were in the constitution of the potash silicates therein. It is now thought that such processes are valueless. In these attempts, the product secured from, for instance. potash feldspar and lime, the design was to lock the lime in the form of an insoluble mono-calcium-aluminum-silicate, freeing the potassa (K 0) for solution. It was not realized that impure feldspars and other potash mineral silicates mixed with free sllica, can be treated preferably at just their sintering temperature after mixing with two molecular weight proportions of lime to each single molecular weight proportion of silica in the mixture, and that after such treatment, the action of carbonic acid and moisture on the product, will cause the alkali aluminate necessarily formed to decompose with liberation'of potassium carbonate, and also will decompose all excess of di-calcium-silicate, with the liberation of soluble calcium bicarbonate and hydrated silica. The residue left after long soil leaching, will, for example, be a calcium potassium zeolite containing in its constitution a variable fraction of a molecule of calcium oxide and a variable fraction of a molecule of potassium oxide (ammonium and other alkali metal oxides may form a part of this fraction) one molecule of alumina and ultimately two molecules of silica together with water of chemical combination, the quantity of which inversely varies to a marked degree with temperatures to which soil waters are naturally subjected. These substances 'are the hydrated feldspars or zeolites of nature. They are permutites, and when immersed in a mixed solution, like soil waters, they reciprocally exchange, especially alkali earth metal oxides and alkalime tal oxides, inclusive of ammonia. These exchanges are governed by the laws of mass action as bearing upon the action of various ions, with variations of temperature and variations of the density of different solutes. Zeolites are recognized as valuable soil constituents.

In the foregoing, I have mentioned the use in a mixture designed to sinter, of two molecular weight proportions of lime or calcium carbonate to each single molecular Weight proportion of silica. In this case, after treatment with (30,, such alumina as may be present in the mixture is left free as hydrated alumina and it naturally enters into combination with hydrated silica to form hydrated alumina silicates (A1 0 .2SiO wH O) or the insoluble clay substances of soils. In

smaller amounts.

doing this,-however, lime adheres naturally to the compound and some alkali metal oxide, therefore, if a slight excess of lime over and above the two molecules of C20 to one of SiO be employed in the mixture, if sintered well, it will free the alkali metal oxides during leaching with greater facility, and it may be supplied in excess even to the extent of an added molecular weight proportion of lime to each single molecular weight proportion of alumina in the total mixture.

One method of producing the di-calcium silicate as a source of soluble hydrated silica, is set forth in a pending application Serial No. 62486, and is substantially as follows: a mixture containing feldspar, leucite 01' like silicates, artificial or natural, is sintered after being mixed with lime in such proportions as there shall be present in the mixture two molecular weight proportions of lime to one of silica, and such proportions of alkali metal oxide to alumina that there can be leached out of the sinter alkali aluminate,

leaving an insoluble di-calcium silicate, plus a variable amount of zeolitic material.

Hydrated calcium silicates can be produced by treating infusorial earth, best when high in water of chemical combination, with slacked lime at ordinary temperatures. Infusorial-earth may contain as high as thirteen per cent of water. This reaction does not take place with round crystalline silica, thus native hydrated silica may, by treating with slacked lime and water, produce calcium silicates suitable for use.

If the described more soluble types of hydrated silica, or-the utilizable calcium silicates, be added to a soil devoid of any one of the other essential mineral fertilizer salts,

such as a nitrogen. compound, no valuable results would be expected. In most soils, these other essential salts occur in greater or IVhen calcium silicate is added, there is formed calcium bicarbonate in the waters of the soil. It is known that calcium bicarbonate acting on hydrated silicates containing potassium oxide and alumina, will liberate potassium oxide to form bicarbonate of potassium, and, therefore, the lime performs a double function of supplying lime to the soil waters and also soluble potassium salts. While the foregoing is known, one must conclude that the acid properties of silicic acid tend to release phosphoric acid from its insoluble combination in the soil, thusalso performing a double function. For maximum growth of plants, deficiencies in all essential mineral fertilizers below that which is required for their full growths, should be supplied to their soil waters in soluble form.

I have made comparative plant experiments usin chemically equlvalent calcium oxide ((M5)) lime proportions in dicalcium-silicate, calcium carbonate, calcium rowth hydrate, calcium carbonate plus hydrated silica mixed therewith, and calcium hydrate plus hydrated silica in mixture, in soils both completely and partially devoid of lime, and found that in those cases where I was supplying hydrated silica to the soil, even as low as one quarter of a ton to the acre, such supply has greatly augmented the growth and luxuriance of nearly all the many plants submitted to competitive tests. These experiments have been performed both in pots and on plots of land, and with each plant, repeated comparative experiments have been made, and in many cases repeated several times. The aggregate result of this work has proven that silica in soluble form is needed to make up that deficiency that exists in all soils that have been submitted to long cultivation.

I find this also true when I supply lime, silica and potash secured by taking a low grade potash feldspar, potash micas or mixtures of the like with silica, that has been sintered with lime to furnish at least the two molecular weight proportions of lime to each single molecular weight proportion of silica in the mixture. Experiments with such a sinter, I have carried on parallel with those that have been mentioned above, and the same show, in many cases, an improvement over using the proper proportioned amount of calcium silicate or lime plus silica. I, therefore, have discovered that low grade potash containing rocks can, if properly sintered or melted with lime (or limestone) be made to give up to the soil waters, hydrated silica, with potassa K 0 and most of the lime employed, whilst a part of the lime will remain to form-a calcium zeolite (or the like) with a relatively lower amount of contained silica than is in any of the pure double silicate minerals of said rocks from which such zeolite or permute materials will slowly form, by action of carbonic acid and water. I consider this of great importance. lleretofore, all efforts have been in the dircction of utilizing only potassa (K 0) from minerals containing it. High grade minerals in potassium oxide in this case are required. The proper proportioning of lime to silica has never been appreciated in these old attempts to produce fertilizers from such rocks and mineral mixtures.

form calcium nitrate or a mixture of cal cium nitrate with potassium nitrate and hydrated silica, I consider a part of my invention together with the intentional use of the hydrated silica in conjunction with said nitrates. The di-calciuni-silicate produced by the process described in my pending application already mentioned, as it is very porous in its structure, can be utilized very effectively by the above treatment.

Proper fineness of the materials I have mentioned, when applied to the soil. can be easily appreciated by all those skilled in the art, and such fineness of division was carefully observed in using the mixtures mentioned in the competitive plant growth experiments already described.

A good fineness for the fertilizer as applied to the soil is represented by the dicalcium silicate passed through an mesh sieve.

I disclaim the use of soluble alkali metal silicates for application to the soil or to add to fertilizer mixtures as a source of supply of soluble silica. Plant growth experiments, long ago abandoned, made with them, have led plant physiologists into the error of considering the soluble types of silica as non-essential in the fertilization of plants. These old experiments failed for a chemical reason that has not been recognized in this art, namely: All soils fertilized, or not, that are suitable for plant growth, must contain calcium hydrate or a salt of calcium. The action of soluble ltun alkali silicates when in solution and brought v in contact with calcium salts, leads to the formation of insoluble compounds formed of lime, alkali metal oxide and silica. When these old experiments were made, as there was always employed an excess of calcium, or lime salt, above that necessary to form this insoluble product, such insoluble salts formed. Therefore, when the experimenters thought they were furnishing soluble silica to the soil water, this silica was being immediately precipitated out and so rendered non-available to their plants. The deductions drawn from their experiments were, therefore, misleading. These deductions have found their way into the literature of this art. Looking up of the silica occurs even with clay present, or with zeolites in the soil, when soluble alkali silicates are used. The silica enters into combination to replace silica that has formerly been leached away from zeolites during their slow process of degradation to clay. From these causes the old comparative plant growth experiments failed to show the value of silica hydrates. This should have been recognized from the art relating to the manufacture of artificial stone from alkali silicates or water glass and said lime compounds. Also from the work performed by Daubree, T. Sterry Hunt and others on the reaction of alkali silicates in the artificial 1. A. fertilizer one of whose components,

is hydrated silica containing more than 15% of water of hydration, and being more soluble than the amorphous types of silica, clay, quartz, feldspar or other natural minerals.

2. A fertilizer formed by adding to fertilizers deficient in soluble silica, an artificially prepared soluble silica containing more than 15% of Water of hydration, and

more soluble than silica contained in quartz, amorphous silica, feldspar and clay occurring in native mineral soils.

3. A fertilizer containing as one of its elements hydrated silica more soluble than 20 ALFRED HUTOHINSON COVLES. Witnesses:

MARGARET HARNED,

FRANK.NEER. 

